1. Field of the Invention
The present invention relates to an apparatus for folding front and rear flaps in a high speed wraparound caser, in which caser when a flat sheet delivered from a magazine is being transported as placed on a sheet receiver of a case transporting conveyor, an article is fed onto the same sheet while the article is being delivered in the same direction as the direction of traveling of the sheet by means of an article transporting conveyor and a dead plate, flaps provided at the front, rear, left and right locations of the same sheet are folded, and then pasting, pressing and pressure-sticking are effected.
2. Description of the Prior Art
At first, a wraparound caser in the prior art will be explained with reference to FIGS. 8 and 9. In these figures, reference numeral (100) designates a vacuum cup arm which is interconnected with a link (101) via a rotatably supported pin (102), and hence the vacuum cup arm (100) and the link (101) can rock integrally about the pin (102) forming a fulcrum point. Reference numeral (103) designates a driving link; a link (104) and a link (105) are successively articulated to the link (103), and a four-articulate linkage is formed by these links. In addition, if a link (107) that is pivotably mounted at an appropriate point (106) on the same link (104) is rotatably articulated to the above-described link (101), then in response to rotation of the driving link (103), the vacuum cup arm (100) would rock between a position (100a) and a position (100b) and would perform an intermittent motion in which it stops for a predetermined period at the position (100b).
On the other hand, in another four-articulate linkage including a link (108) as a driving link and formed of that driving link (108) and links (109) and (110), an appropriate point (111) on the link (109) would depict an elliptic locus in response to rotation of the driving link (108). Reference numeral (112) designates case pushers which are fixedly secured to mount bars (112a) that is rotatably mounted at the point (111) on the link (109). In addition, if a guide bar (114) that is freely slidable with respect to a housing (113) rotatably mounted on a machine wall (not shown) is fixedly secured to the mount bar (112a), then in response to rotation of the driving link (108), the case pusher (112) performs forward and backward traveling motions as well as a jumping motion in the proximity of the forward traveling end. Reference numeral (115) designates suction arms which are rocked by a cam mechanism not shown, and vacuum cups (116a) and (116b) are mounted at their tip ends. Reference numeral (117) designates a seam hook that is rocked by a cam mechanism not shown, reference numerals (118a) and (118b) designate side hooks which are rocked by a cam mechanism not shown, numerals (119a) and (119b) designate bottom flap tackers which are rocked by a cam mechanism not shown, and numerals (120) and (121) designate bucket conveyor guides provided on chains (122) which are stretched in an endless form.
In the above-described wraparound caser, the driving links (103) and (108), the respective cams for driving the suction arm (115), the seam hook (117), the side hooks (118a) and (118b) and the bottom flap tackers (119a) and (119b), respectively, and the chains (122) of the bucket conveyor are regulated in their mutual timing, and so, they are driven in a synchronized manner. Each of flat blank sheets (125) stacked in a magazine is sucked by vacuum cups (124) mounted on the vacuum cup arm (100) at its position (100a), and when it moves to its position (100b), it is folded into a U-shape as shown at (124') by fixed guides (126) and (127). At this time, bottom flaps of the blank sheet are pressed on transporting rails (128) by means of the bottom flap tacker (119a) and (119b) to prevent the folded sheet or the case from floating up. During the period when the vacuum cup arm (100) stops for a while under such condition, the case pushers (112) deliver the case (124') folded into a U-shape to the bucket conveyor, in which the case (124') folded into a U-shape is transported as sandwiched by the bucket conveyor guides (120) and (121) while the bottom flaps are pressed by fixed guides (129).
Although the above-described operation is satisfactory upon low speed operation, if the apparatus enters high speed operation, when the flat blank sheet (124) is sucked at the position (100a), pick-up of the blank sheet becomes difficult due to a vacuum force generated by the abrupt separation of the overlapped flat blank sheets (124). In order to obviate this difficulty, a single sheet separation mechanism for the flat blank sheets is provided. More particularly, this mechanism is composed of the suction arms (115) which are rocked by a cam mechanism, the seam hook (117) and the side hooks (118a) and (118b). At the timing when the vacuum cups (116a) and (116b) on the suction arms (115) suck the flat blank sheet (124) at the bottom of the magazine (123), the seam hook (117) releases the blank sheets (124) and the side hooks (118a) and (118b) support the blank sheets (124). When the suction arm (115) has rocked and one of the blank sheets (124) has been separated, the seam hook (117) is rocked in the direction for pressing the blank sheets (124) to support the remaining blank sheets (124), thereafter the side hooks (118a) and (118b) are released, and the blank sheet (124) at the bottom can be perfectly separated from the other blank sheets (124). At this timing, pick-up of the blank sheet becomes possible by effecting suction of the blank sheet by the vacuum cups (125) on the above-described vacuum cup arm (100).
In the wraparound caser in the prior art shown in FIGS. 8 and 9, since the sheet (124') pulled out from the magazine (123) and shaped into a U-shape by a shaping device is transported by merely supporting the front and rear flaps of the shaped sheet (124') with the bucket conveyor guides (120) and (121) fixedly mounted to the chains (122) of the bucket conveyor stretched in an endless manner, it is difficult to adjust the erect shaping angle of the bucket conveyor guides (120) and (121) during the transportation. Also, besides the case transporting conveyor, a shaping device and an article feeding device for feeding an article along a direction perpendicular to the direction of traveling of the conveyor are necessitated, and there is a fear that a fed article may drop out of the sheet (124') shaped into a U-shape. In addition, the entire wraparound caser becomes large-sized due to the above-mentioned respective devices, a wide space is required for installation of the wraparound caser, and a high cost results. Furthermore, there is a problem that the structure of the wraparound caser is complex and a lot of time is required for maintenance.